SEOUL, South Korea - Authorities in South Korea temporarily closed two hospitals amid persistent fears over the MERS virus outbreak, which killed an 11th person Friday, though health officials said they are seeing fewer new infections.

More than 120 people in South Korea have been diagnosed with Middle East respiratory syndrome since the country reported its first case last month. The outbreak, the largest outside Saudi Arabia, has been occurring only in hospitals, among patients, family members who visited them and medical staff treating them. Still, it has caused widespread fears and rumours, and about 2,790 schools and kindergartens remained closed Friday.

South Korean officials believe the disease has peaked and it would begin easing in coming days. Their assessment is based on a view that the virus' maximum two-week incubation period for those infected at a Seoul hospital considered as the main source of the outbreak ended Friday.

However, there are several other hospitals where additional cases were later reported or MERS patients were treated. Their incubation periods have not ended, raising worries that they may become new sources of infections.

Two of the hospitals, Mediheal Hospital in western Seoul and Changwon SK Hospital in the southern city of Changwon, were ordered Thursday to temporarily shut down after MERS patients were found to have contacted hundreds of people there before they tested positive for the virus, according to officials at Seoul and Changwon.

There are currently no MERS patients at the two hospitals, but dozens of medical staff and existing patients there were being prevented from leaving the facilities as a quarantine measure. Mediheal is to reopen on June 23, and Changwon SK on June 24, city officials said.

Central government officials say there is little chance of the virus spreading from those hospitals because they are quarantining people who had contacts with infected people and monitoring them.

"We see no danger of an additional spread," Jeong Eun-kyeong, a senior official from the Korea Center for Disease Control and Prevention, told a news conference. She said only a small number of new infections could still be reported from those hospitals.

Some experts have said the outbreak could continue if there are a large number of infected people who evaded government quarantine measures and spread the virus.

The Health Ministry on Friday reported just four new MERS cases, after registering 14 cases Thursday and 13 on Wednesday. About 3,680 people were still isolated on Friday after possible contacts with infected people, a decline from more than 3,800 on Thursday, according to the ministry.

Senior ministry official Kwon Deok-cheol told the news conference that the public should stop worrying too much about the outbreak as the number of new cases has been falling.

Most of the deaths so far have been of people suffering from pre-existing medical conditions, such as respiratory problems or cancer.

A 72-year-old MERS patient, who had pneumonia, died Friday and became the country's 11th death linked to the MERS outbreak, the Health Ministry said.

Experts think MERS can spread in respiratory droplets, such as by coughing. But transmissions have mainly occurred through close contact, such as living with or caring for an infected person.

MERS has mostly been centred in Saudi Arabia and has a death rate of about 40 per cent among reported cases. It belongs to the family of coronaviruses that includes the common cold and SARS, and can cause fever, breathing problems, pneumonia and kidney failure.